System

New concept definition for {{entity:Kids Remote Control Airplane}} ({{hex:DEEC5058}}), a consumer radio-controlled fixed-wing aircraft designed for children aged 8–14. The system comprises a handheld 2.4 GHz transmitter, a foam airframe with brushless electric propulsion, electronic speed controller, servos, gyro stabiliser, LiPo battery, and a USB balance charger. The domain is consumer toys/hobby electronics — the 21st completed system and a departure from prior heavy-industrial and defence domains into child-safety-critical consumer product territory. Project scaffolded as se-kids-remote-control-airplane in the SE:kids-remote-control-airplane namespace.

ConOps

Six operating modes identified and classified: {{entity:Pre-flight Check mode of Kids Remote Control Airplane}} ({{hex:54882A00}}), {{entity:Normal Flight mode of Kids Remote Control Airplane}} ({{hex:54FC3218}}), {{entity:Signal Loss Failsafe mode of Kids Remote Control Airplane}} ({{hex:40B53A00}}), {{entity:Battery Critical Emergency Landing mode of Kids Remote Control Airplane}} ({{hex:54F47A00}}), {{entity:Battery Charging mode of Kids Remote Control Airplane}} ({{hex:54F47200}}), and {{entity:Post-crash Inspection and Repair mode of Kids Remote Control Airplane}} ({{hex:44881A08}}).

Five ConOps scenarios written in operational language: (1) Weekend Park Flight — the happy-path 25-minute session with hand launch, circuits at 15 m, and belly landing on grass. (2) Wind Gust Crash and Recovery — 15 kt gust causes stall and nose-dive, child performs field repair with spare propeller and CA glue. (3) Signal Loss Failsafe — aircraft flies behind trees, failsafe cuts motor and glides to a neighbouring field. (4) LiPo Fire During Charging — crash-damaged battery develops internal short during charge; charger alarm triggers parent intervention before thermal runaway. (5) Routine Maintenance — battery lifecycle replacement after 30 cycles, hinge and pushrod inspection.

Hazard Register

ID	Hazard	Severity	Freq	SIL	Safe State
H-001	Propeller strike laceration/eye injury	Critical	Medium	2	Motor de-energised, propeller stationary
H-002	LiPo thermal runaway and fire	Catastrophic	Rare	2	Battery disconnected, isolated in fireproof bag
H-003	Flyaway beyond VLOS striking people/property	Critical	Low	1	Motor cut, failsafe glide descent
H-004	Falling aircraft striking bystander	Major	Medium	1	Motor off, aircraft on ground
H-005	Burns from short-circuit in exposed wiring	Major	Low	1	Battery connector unplugged
H-006	RF interference causing cross-control	Critical	Rare	1	Receiver failsafe on loss of bound signal
H-007	Small parts choking hazard for siblings <3	Critical	Low	1	Parts secured, battery compartment child-proofed

The two SIL-2 hazards (H-001 propeller strike and H-002 LiPo fire) will drive safety requirements for propeller guards, motor-arm interlocks, and charger cell monitoring in the scaffold session.

Stakeholders

Stakeholder	Hex	Relationship
{{entity:Child Pilot (RC Airplane Operator)}}	{{hex:00080000}}	Primary operator, all flight modes
{{entity:Supervising Parent or Guardian}}	{{hex:000C08A1}}	Supervisor, maintenance, purchase decision
{{entity:Park Bystanders and Public}}	{{hex:04000001}}	Passive exposure to impact risk
{{entity:RC Airplane Product Manufacturer}}	{{hex:40843859}}	Design, manufacture, compliance
{{entity:Toy Safety and Aviation Regulatory Authority}}	{{hex:008578FD}}	EN 71, ASTM F963, FCC Part 15, sub-250 g rules
{{entity:Consumer Electronics and Toy Retailer}}	{{hex:408410D8}}	Distribution, LiPo shipping, returns

Operating Environment

Physical: -5 °C to 40 °C operating, wind 0–15 kt normal / >25 kt no-fly, humidity 0–95 % non-condensing, sea level to 2000 m AMSL. Electromagnetic: 2.4 GHz ISM band shared with WiFi/Bluetooth, must tolerate co-channel interference per FCC Part 15. Operational space: minimum 50 × 50 m clear area, VLOS only, maximum 200 m typical range, 120 m AGL ceiling. Regulatory: EN 71 (EU), ASTM F963 (US), CE/UKCA marking, sub-250 g preferred for registration exemption.

External Interfaces

External System	Hex	Interface
{{entity:USB Power Supply for Battery Charger}}	{{hex:D48C0008}}	5 V / 2 A USB for balance charger
{{entity:Atmosphere as aerodynamic medium}}	{{hex:06010000}}	Lift, drag, wind disturbance
{{entity:2.4 GHz ISM Radio Spectrum}}	{{hex:04056858}}	FHSS control link, <1 W EIRP
Ground surface	—	Landing/crash energy absorption

flowchart TB
  SYS["Kids RC Airplane System"]
  CP(["Child Pilot"])
  PG(["Parent/Guardian"])
  BY(["Bystanders"])
  AT["Atmosphere"]
  USB["USB Power Supply"]
  RF["2.4 GHz ISM Band"]
  GND["Ground Surface"]
  CP -->|Control commands| SYS
  SYS -->|Visual/audible feedback| CP
  PG -->|Supervision, maintenance| SYS
  SYS -->|Noise, visual, impact risk| BY
  AT -->|Lift, drag, wind disturbance| SYS
  USB -->|5V charge power| SYS
  RF -->|2.4GHz radio link| SYS
  SYS -->|Landing/crash forces| GND

Next

The scaffold session (485) should derive stakeholder requirements from the ConOps scenarios — particularly from the two SIL-2 hazards (propeller strike, LiPo fire) which demand safety requirements with quantified performance thresholds. System functions to identify: flight control, power management, radio link management, structural integrity, and charging safety. The sub-250 g mass constraint will strongly influence architecture — every gram allocated to a propeller guard or charger circuit is a gram removed from airframe or battery capacity. Functional grouping should cluster around the transmitter/receiver boundary, the power/propulsion chain, and the airframe/control-surfaces group.